From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.kapsi.fi ([217.30.184.167]:42754 "EHLO mail.kapsi.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753703Ab3KERA6 (ORCPT ); Tue, 5 Nov 2013 12:00:58 -0500 Message-ID: <52792446.1020109@iki.fi> Date: Tue, 05 Nov 2013 19:00:54 +0200 From: Antti Palosaari MIME-Version: 1.0 To: Mauro Carvalho Chehab , unlisted-recipients:; CC: Linux Media Mailing List , Mauro Carvalho Chehab Subject: Re: [PATCH v3 13/29] [media] dvb-frontends: Don't use dynamic static allocation References: <1383645702-30636-1-git-send-email-m.chehab@samsung.com> <1383645702-30636-14-git-send-email-m.chehab@samsung.com> In-Reply-To: <1383645702-30636-14-git-send-email-m.chehab@samsung.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Acked-by: Antti Palosaari Reviewed-by: Antti Palosaari Antti On 05.11.2013 12:01, Mauro Carvalho Chehab wrote: > Dynamic static allocation is evil, as Kernel stack is too low, and > compilation complains about it on some archs: > drivers/media/dvb-frontends/af9013.c:77:1: warning: 'af9013_wr_regs_i2c' uses dynamic stack allocation [enabled by default] > drivers/media/dvb-frontends/af9033.c:188:1: warning: 'af9033_wr_reg_val_tab' uses dynamic stack allocation [enabled by default] > drivers/media/dvb-frontends/af9033.c:68:1: warning: 'af9033_wr_regs' uses dynamic stack allocation [enabled by default] > drivers/media/dvb-frontends/bcm3510.c:230:1: warning: 'bcm3510_do_hab_cmd' uses dynamic stack allocation [enabled by default] > drivers/media/dvb-frontends/cxd2820r_core.c:84:1: warning: 'cxd2820r_rd_regs_i2c.isra.1' uses dynamic stack allocation [enabled by default] > drivers/media/dvb-frontends/rtl2830.c:56:1: warning: 'rtl2830_wr' uses dynamic stack allocation [enabled by default] > drivers/media/dvb-frontends/rtl2832.c:187:1: warning: 'rtl2832_wr' uses dynamic stack allocation [enabled by default] > drivers/media/dvb-frontends/tda10071.c:52:1: warning: 'tda10071_wr_regs' uses dynamic stack allocation [enabled by default] > drivers/media/dvb-frontends/tda10071.c:84:1: warning: 'tda10071_rd_regs' uses dynamic stack allocation [enabled by default] > > Instead, let's enforce a limit for the buffer. Considering that I2C > transfers are generally limited, and that devices used on USB has a > max data length of 64 bytes for the control URBs. > > So, it seem safe to use 64 bytes as the hard limit for all those devices. > > On most cases, the limit is a way lower than that, but this limit > is small enough to not affect the Kernel stack, and it is a no brain > limit, as using smaller ones would require to either carefully each > driver or to take a look on each datasheet. > > Signed-off-by: Mauro Carvalho Chehab > --- > drivers/media/dvb-frontends/af9013.c | 12 +++++++++++- > drivers/media/dvb-frontends/af9033.c | 21 +++++++++++++++++++-- > drivers/media/dvb-frontends/cxd2820r_core.c | 21 +++++++++++++++++++-- > drivers/media/dvb-frontends/rtl2830.c | 12 +++++++++++- > drivers/media/dvb-frontends/rtl2832.c | 12 +++++++++++- > drivers/media/dvb-frontends/tda10071.c | 21 +++++++++++++++++++-- > 6 files changed, 90 insertions(+), 9 deletions(-) > > diff --git a/drivers/media/dvb-frontends/af9013.c b/drivers/media/dvb-frontends/af9013.c > index a204f2828820..19ba66ad23fa 100644 > --- a/drivers/media/dvb-frontends/af9013.c > +++ b/drivers/media/dvb-frontends/af9013.c > @@ -24,6 +24,9 @@ > > #include "af9013_priv.h" > > +/* Max transfer size done by I2C transfer functions */ > +#define MAX_XFER_SIZE 64 > + > struct af9013_state { > struct i2c_adapter *i2c; > struct dvb_frontend fe; > @@ -50,7 +53,7 @@ static int af9013_wr_regs_i2c(struct af9013_state *priv, u8 mbox, u16 reg, > const u8 *val, int len) > { > int ret; > - u8 buf[3+len]; > + u8 buf[MAX_XFER_SIZE]; > struct i2c_msg msg[1] = { > { > .addr = priv->config.i2c_addr, > @@ -60,6 +63,13 @@ static int af9013_wr_regs_i2c(struct af9013_state *priv, u8 mbox, u16 reg, > } > }; > > + if (3 + len > sizeof(buf)) { > + dev_warn(&priv->i2c->dev, > + "%s: i2c wr reg=%04x: len=%d is too big!\n", > + KBUILD_MODNAME, reg, len); > + return -EINVAL; > + } > + > buf[0] = (reg >> 8) & 0xff; > buf[1] = (reg >> 0) & 0xff; > buf[2] = mbox; > diff --git a/drivers/media/dvb-frontends/af9033.c b/drivers/media/dvb-frontends/af9033.c > index a777b4b944eb..11f1555e66dc 100644 > --- a/drivers/media/dvb-frontends/af9033.c > +++ b/drivers/media/dvb-frontends/af9033.c > @@ -21,6 +21,9 @@ > > #include "af9033_priv.h" > > +/* Max transfer size done by I2C transfer functions */ > +#define MAX_XFER_SIZE 64 > + > struct af9033_state { > struct i2c_adapter *i2c; > struct dvb_frontend fe; > @@ -40,7 +43,7 @@ static int af9033_wr_regs(struct af9033_state *state, u32 reg, const u8 *val, > int len) > { > int ret; > - u8 buf[3 + len]; > + u8 buf[MAX_XFER_SIZE]; > struct i2c_msg msg[1] = { > { > .addr = state->cfg.i2c_addr, > @@ -50,6 +53,13 @@ static int af9033_wr_regs(struct af9033_state *state, u32 reg, const u8 *val, > } > }; > > + if (3 + len > sizeof(buf)) { > + dev_warn(&state->i2c->dev, > + "%s: i2c wr reg=%04x: len=%d is too big!\n", > + KBUILD_MODNAME, reg, len); > + return -EINVAL; > + } > + > buf[0] = (reg >> 16) & 0xff; > buf[1] = (reg >> 8) & 0xff; > buf[2] = (reg >> 0) & 0xff; > @@ -161,7 +171,14 @@ static int af9033_wr_reg_val_tab(struct af9033_state *state, > const struct reg_val *tab, int tab_len) > { > int ret, i, j; > - u8 buf[tab_len]; > + u8 buf[MAX_XFER_SIZE]; > + > + if (tab_len > sizeof(buf)) { > + dev_warn(&state->i2c->dev, > + "%s: i2c wr len=%d is too big!\n", > + KBUILD_MODNAME, tab_len); > + return -EINVAL; > + } > > dev_dbg(&state->i2c->dev, "%s: tab_len=%d\n", __func__, tab_len); > > diff --git a/drivers/media/dvb-frontends/cxd2820r_core.c b/drivers/media/dvb-frontends/cxd2820r_core.c > index d9eeeb1dfa96..03930d5e9fea 100644 > --- a/drivers/media/dvb-frontends/cxd2820r_core.c > +++ b/drivers/media/dvb-frontends/cxd2820r_core.c > @@ -21,12 +21,15 @@ > > #include "cxd2820r_priv.h" > > +/* Max transfer size done by I2C transfer functions */ > +#define MAX_XFER_SIZE 64 > + > /* write multiple registers */ > static int cxd2820r_wr_regs_i2c(struct cxd2820r_priv *priv, u8 i2c, u8 reg, > u8 *val, int len) > { > int ret; > - u8 buf[len+1]; > + u8 buf[MAX_XFER_SIZE]; > struct i2c_msg msg[1] = { > { > .addr = i2c, > @@ -36,6 +39,13 @@ static int cxd2820r_wr_regs_i2c(struct cxd2820r_priv *priv, u8 i2c, u8 reg, > } > }; > > + if (1 + len > sizeof(buf)) { > + dev_warn(&priv->i2c->dev, > + "%s: i2c wr reg=%04x: len=%d is too big!\n", > + KBUILD_MODNAME, reg, len); > + return -EINVAL; > + } > + > buf[0] = reg; > memcpy(&buf[1], val, len); > > @@ -55,7 +65,7 @@ static int cxd2820r_rd_regs_i2c(struct cxd2820r_priv *priv, u8 i2c, u8 reg, > u8 *val, int len) > { > int ret; > - u8 buf[len]; > + u8 buf[MAX_XFER_SIZE]; > struct i2c_msg msg[2] = { > { > .addr = i2c, > @@ -70,6 +80,13 @@ static int cxd2820r_rd_regs_i2c(struct cxd2820r_priv *priv, u8 i2c, u8 reg, > } > }; > > + if (len > sizeof(buf)) { > + dev_warn(&priv->i2c->dev, > + "%s: i2c wr reg=%04x: len=%d is too big!\n", > + KBUILD_MODNAME, reg, len); > + return -EINVAL; > + } > + > ret = i2c_transfer(priv->i2c, msg, 2); > if (ret == 2) { > memcpy(val, buf, len); > diff --git a/drivers/media/dvb-frontends/rtl2830.c b/drivers/media/dvb-frontends/rtl2830.c > index 362d26d11e82..b908800b390d 100644 > --- a/drivers/media/dvb-frontends/rtl2830.c > +++ b/drivers/media/dvb-frontends/rtl2830.c > @@ -27,11 +27,14 @@ > > #include "rtl2830_priv.h" > > +/* Max transfer size done by I2C transfer functions */ > +#define MAX_XFER_SIZE 64 > + > /* write multiple hardware registers */ > static int rtl2830_wr(struct rtl2830_priv *priv, u8 reg, const u8 *val, int len) > { > int ret; > - u8 buf[1+len]; > + u8 buf[MAX_XFER_SIZE]; > struct i2c_msg msg[1] = { > { > .addr = priv->cfg.i2c_addr, > @@ -41,6 +44,13 @@ static int rtl2830_wr(struct rtl2830_priv *priv, u8 reg, const u8 *val, int len) > } > }; > > + if (1 + len > sizeof(buf)) { > + dev_warn(&priv->i2c->dev, > + "%s: i2c wr reg=%04x: len=%d is too big!\n", > + KBUILD_MODNAME, reg, len); > + return -EINVAL; > + } > + > buf[0] = reg; > memcpy(&buf[1], val, len); > > diff --git a/drivers/media/dvb-frontends/rtl2832.c b/drivers/media/dvb-frontends/rtl2832.c > index a95dfe0a5ce3..cd1e6965ac11 100644 > --- a/drivers/media/dvb-frontends/rtl2832.c > +++ b/drivers/media/dvb-frontends/rtl2832.c > @@ -22,6 +22,9 @@ > #include "dvb_math.h" > #include > > +/* Max transfer size done by I2C transfer functions */ > +#define MAX_XFER_SIZE 64 > + > int rtl2832_debug; > module_param_named(debug, rtl2832_debug, int, 0644); > MODULE_PARM_DESC(debug, "Turn on/off frontend debugging (default:off)."); > @@ -162,7 +165,7 @@ static const struct rtl2832_reg_entry registers[] = { > static int rtl2832_wr(struct rtl2832_priv *priv, u8 reg, u8 *val, int len) > { > int ret; > - u8 buf[1+len]; > + u8 buf[MAX_XFER_SIZE]; > struct i2c_msg msg[1] = { > { > .addr = priv->cfg.i2c_addr, > @@ -172,6 +175,13 @@ static int rtl2832_wr(struct rtl2832_priv *priv, u8 reg, u8 *val, int len) > } > }; > > + if (1 + len > sizeof(buf)) { > + dev_warn(&priv->i2c->dev, > + "%s: i2c wr reg=%04x: len=%d is too big!\n", > + KBUILD_MODNAME, reg, len); > + return -EINVAL; > + } > + > buf[0] = reg; > memcpy(&buf[1], val, len); > > diff --git a/drivers/media/dvb-frontends/tda10071.c b/drivers/media/dvb-frontends/tda10071.c > index e79749cfec81..1d8bc2ea4b10 100644 > --- a/drivers/media/dvb-frontends/tda10071.c > +++ b/drivers/media/dvb-frontends/tda10071.c > @@ -20,6 +20,9 @@ > > #include "tda10071_priv.h" > > +/* Max transfer size done by I2C transfer functions */ > +#define MAX_XFER_SIZE 64 > + > static struct dvb_frontend_ops tda10071_ops; > > /* write multiple registers */ > @@ -27,7 +30,7 @@ static int tda10071_wr_regs(struct tda10071_priv *priv, u8 reg, u8 *val, > int len) > { > int ret; > - u8 buf[len+1]; > + u8 buf[MAX_XFER_SIZE]; > struct i2c_msg msg[1] = { > { > .addr = priv->cfg.demod_i2c_addr, > @@ -37,6 +40,13 @@ static int tda10071_wr_regs(struct tda10071_priv *priv, u8 reg, u8 *val, > } > }; > > + if (1 + len > sizeof(buf)) { > + dev_warn(&priv->i2c->dev, > + "%s: i2c wr reg=%04x: len=%d is too big!\n", > + KBUILD_MODNAME, reg, len); > + return -EINVAL; > + } > + > buf[0] = reg; > memcpy(&buf[1], val, len); > > @@ -56,7 +66,7 @@ static int tda10071_rd_regs(struct tda10071_priv *priv, u8 reg, u8 *val, > int len) > { > int ret; > - u8 buf[len]; > + u8 buf[MAX_XFER_SIZE]; > struct i2c_msg msg[2] = { > { > .addr = priv->cfg.demod_i2c_addr, > @@ -71,6 +81,13 @@ static int tda10071_rd_regs(struct tda10071_priv *priv, u8 reg, u8 *val, > } > }; > > + if (len > sizeof(buf)) { > + dev_warn(&priv->i2c->dev, > + "%s: i2c wr reg=%04x: len=%d is too big!\n", > + KBUILD_MODNAME, reg, len); > + return -EINVAL; > + } > + > ret = i2c_transfer(priv->i2c, msg, 2); > if (ret == 2) { > memcpy(val, buf, len); > -- http://palosaari.fi/